Biocide

Abstract

A method of treating an aqueous or non-aqueous dfsystem is disclosed which comprises adding to the system a thiolan of the formula ##STR1## wherein each of X and Y, which may be the same or different, represents fluorine, chlorine or bromine, in combination with a sulphone of the formula: ##STR2## in which R 1 represents an optionally halogenated alkyl radical or an optionally substituted aryl radical, R 2 represents a cyano or amidocarbonyl radical and X represents a halogen atom.

We claim: 
     
       1. A biocidal composition suitable for addition to an aqueous system which comprises a synergistically effective combination of a thiolan of the formula: ##STR8## wherein each of X and Y represents chlorine, and a sulphone of the formula: ##STR9## in which R 1  represents a phenyl radical, R 2  represents a cyano radical and X represents chlorine; the thiolan and the sulphone being present in a weight ratio of the thiolan to the sulphone of from about 1:15 to 1:1. 
     
     
       2. A composition according to claim 1, in which the weight ratio of the thiolan to the sulphone is from about 1:5 to 1:1.2. 
     
     
       3. A composition according to claim 1 in which the weight ratio of thiolan to sulphone is from 1:15 to 1:1.2. 
     
     
       4. A composition according to claim 1 which comprises in addition to said active ingredients, a solvent and optionally a dispersing agent, and which contains a total of from 2% to 8% by weight of the active ingredients. 
     
     
       5. A composition according to claim 1 which is in the form of a solution in a hydrophilic organic solvent. 
     
     
       6. A composition according to claim 5 in which the solvent is butyl diglycol, a polyethylene glycol, 2-butoxy ethanol, propylene glycol, a polypropylene glycol or diethylene glycol. 
     
     
       7. A composition according to claim 1 which also contains a dispersing agent. 
     
     
       8. A composition according to claim 7 in which the dispersing agent is an ethoxylated phenol having the general formula: ##STR10## where m represents 2 to 40 and R represents C n  H 2n+  1 in which n is from 0 to 18. 
     
     
       9. A composition according to claim 7 in which the ratio of dispersing agent to active ingredient is from 1:1.6 to 1.25:1. 
     
     
       10. A method of treating an aqueous or non-aqueous system containing fungal or bacterial contaminants or both, to control said contaminants, which comprises adding to the system a thiolan of the formula ##STR11## wherein each of X and Y represents chlorine, in combination with a sulphone of the formula: ##STR12## in which R 1  represents a phenyl radical, R 2  represents a cyano radical and X represents chlorine; the thiolan and the sulphone being added to the system in a weight ratio of the thiolan to the sulphone of from about 1:15 to 1:1 and in amounts effective for said thiolan and said sulphone to provide interactive protection of the system from said contaminants. 
     
     
       11. A method according to claim 10 in which the weight ratio of the thiolan to the sulphone is from about 1:5 to 1:1.2. 
     
     
       12. A method according to claim 10 in which the system is a water-cooling or an aqueous system used in paper-making. 
     
     
       13. A method according to claim 10 in which the weight ratio of thiolan to sulphone is from 1:15 to 1:1.2. 
     
     
       14. A method according to claim 10 in which the combination of active ingredients is added in an amount from 0.1 to 40 ppm. 
     
     
       15. A method according to claim 10 for treating a cooling water system or an aqueous system used in paper -making which comprises adding to the system said thiolan and said sulphone in a weight ratio of 1:15 to 1:1.2, the total concentration of thiolan and sulphone being from 0.1 to 40 ppm.   
     
     
       16. A method according to claim 10 wherein both fungal and bacterial contaminants are present in the system prior to treatment.